Introduction to Cell and Tissue Structure

Question 1

Endocytosis

Answer 1

Plasma membrane folds to form intracellular vesicle that pinches off

Question 2

Phagocytosis

Answer 2

Engulfing large particles

Question 3

Pinocytosis

Answer 3

Engulfing small particles. Mediated via receptor/ligand binding.

Question 4

Exocytosis

Answer 4

Intracellular vesicle fuses with the plasma membrane to release material inside the vesicle to extracellular space

Question 5

Nucleus

Answer 5

Contains nucleoplasm and chromatin

Question 6

Nuclear envelope

Answer 6

Double membrane with channels through both membranes (nuclear pores)

Question 7

Nuclear lamina

Answer 7

Fibrous meshwork formed by proteins called lamins

Question 8

Nuclear pore complex

Answer 8

Formed by specific proteins that regulate movement of material (RNAs, proteins, and ribosome subunits) in and out of nucleus

Question 9

Nucleolus

Answer 9

Site of rRNA transcription and ribosome subunit assembly

Question 10

Rough endoplasmic reticulum

Answer 10

Lipid synthesis, glycogenesis (making glycogen), detoxification (oxidation and methylation reactions), Ca2+ metabolism in striated muscle

Question 11

Golgi apparatus

Answer 11

Ogliosaccharide chain processing, glycosylation and deglycosylation of proteins and lipids (adding and removing carbohydrates), assembly of proteoglycans (proteins with carbohydrates attached), phosphorylation and sulfation of proteoglycans and proteins, proteolytic processing of polypeptides (cleaving proteins to change function)

Question 12

Endosomes

Answer 12

Associate with receptors to form coated pits and vesicles. Clathrins and clathrin-associated proteins form coat on the cytoplasmic surface of membrane.

Question 13

Early endosomes

Answer 13

May still carry clathrin and surface receptor molecules. Internal acidification leads to receptor ligand separation.

Question 14

Late endosomes

Answer 14

Shed cell surface related components (clathrin, receptors). Fuse with lysosomes.

Question 15

Carrier vesicles (MVBs)

Answer 15

Transfer materials from early to late endosomes

Question 16

Lysosomes

Answer 16

Have lytic enzymes. Fuse with late endosomes to form a secondary lysosome or phagolysosome to digest internalized material.

Question 17

Peroxisomes

Answer 17

Major enzyme is catalase which metabolizes hydrogen peroxide by oxidation of organic substrates. Also contain enzymes for _-oxidation for long chain fatty acids. Some peroxisomes have crystalloid core (not humans) which helps with identification.

Question 18

Mitochondria

Answer 18

Cristae are the site of proteins and enzymes for oxidative phosphorylation and ATPase synthetase complex. Inner membrane matrix contains enzymes for lipid synthesis and modification. Krebs cycle enzymes, DNA and RNA, ribosomes, and enzymes for protein synthesis. May store Ca2+.

Question 19

Microfilaments

Answer 19

Actin (G-Actin) form two chain helical polymer (F-Actin) which is the core of the microfilaments. Actin-associated proteins which bind to actin and modify activity of microfilaments.

Question 20

Microtubules

Answer 20

Tubulin-_ and _ isoforms alternate to form polymeric protofilament. 13 protofilaments aligned side by side make microtubule.

Question 21

Desmin

Answer 21

Intermediate filaments for muscle cells

Question 22

Vimentin

Answer 22

Intermediate filaments for mesenchymal cells (adult stem cells in bone marrow)

Question 23

Neurofilament protein

Answer 23

Intermediate filaments for neuronal cells

Question 24

Keratins

Answer 24

Intermediate filaments for epithelial cells

Question 25

Glial fibrillar proteins

Answer 25

Intermediate filaments for glial cells (support cells in the CNS)

Question 26

Four main tissue types

Answer 26

1. Epithelial 2. Connective 3. Muscle 4. Nerve

Question 27

Epithelial tissue

Answer 27

Line or cover organs, regulate transport of materials, and form glands. Have an apical (top or facing the ECM) and basal (bottom or facing the lumen) surface.

Question 28

Connective tissue

Answer 28

Combination of cells and extra-cellular matrix (ECM). Form skeletal structures, provide conduit for blood vessels and nerves, provide cushoning.

Question 29

Muscle tissue

Answer 29

3 types: 1. Skeletal-attached to skeleton for voluntary body movement 2. Smooth-Component of many organs responsible for autonomic (involuntary) visceral movement 3. Cardiac-forms walls of heart chambers

Question 30

Nerve tissue

Answer 30

Transmits electrical signals which regulate brain function, muscle and gland activity. Composed of neurons (cells which generate and receive electrical signals) and glia (mixed population of cells that provide metabolic and structural support to neurons.